What does it mean when the height of a barometer is falling?

Why does an air bubble formed in water grow in size as it rises from the bottom to the surface? Explain.

$A$ barometer kept in an elevator reads $76 \, cm$ when the elevator is accelerating upwards. The most likely pressure inside the elevator (in $cm$ of $Hg$) is ........

$A$ beaker containing a liquid of density $\rho$ moves up with an acceleration $a$. The pressure due to the liquid at a depth $h$ below the free surface of the liquid is ............

$A$ submarine has a window of area $30 \times 30 \,cm^2$ on its ceiling and is at a depth of $100 \,m$ below sea level. If the pressure inside the submarine is maintained at the sea-level atmospheric pressure,then the force acting on the window is ............. $N$ (consider density of sea water $\rho = 1.03 \times 10^3 \,kg/m^3$,acceleration due to gravity $g = 10 \,m/s^2$).

The figure shows two containers $P$ and $Q$ with the same base area $A$,each filled to the same height with the same liquid. Select the correct alternative.